I'm new to large format and will be starting with a crown graphic. I do a fair amount of portraiture and was wondering if the same focal length guidelines for 35mm apply to large format. I've always used a lens of at least twice the frame diagonal (when cropped to 4:5 ratio) to avoid exaggerated perspective. If I apply that rule to 4x5 I get a very long lens, probably even too long to focus at infinity let alone close.

I know different rules apply here because of different magnification ratios between large and small format. I'll be closer to a macro extension than infinity for a face shot. So bottom-line it for me. What should my minimum focal length be for face shots with 4x5? Is it even practical to do that with a Crown or should I look for alternatives like a 6x7 back and 180mm lens or wait until I get a long bellows camera?

I usually use a rule of double the longer of the two dimentions. This gives us about a 10" lens on a 4x5 and Wollensak made a 10" tele-optar that would be good for portraiture. A 12" tele lens would be good too, they made a 15" tele for the Graflex and Graphic, but you would need a pretty long studio for that, and have a couple of 8x10 portrait lenses that are 15" in focal lenght, so maybe it's a bit too long.

The 10"tele lens is preferable over a "normal designed 10" in your situation because a tele lens uses less bellows draw than a normal, so you will be able to focus closer with a tele than with a normal 10" lens.

another lens option would be the 270mm tele-artar and tele rotelar.

except for the 10" tele-optar, these lenses will be on the heavy side, the tele-optar just a bit less so. While it can be done with a graphic, it won't be the sturdiest of cameras for the situation, particularly since you'll have to mount the camera on a tripod in the vertical postion. A kodak 2D or agfa/ansco with a 4x5 back or a Crown View camera would all be sturdier, but bigger and heavier. A Crown View looks just like a 2D but it 4x5. Even a grpahic view would be sturdier than a graphic, but again you trade sturdiness for portability.